The present invention is directed to a sleeve head consisting of a single member of shrinkable material for closing the end of a cable sleeve. The sleeve head has a flanged opening in a wall to form a sealable cable inlet for allowing insertion of the cable into the cable sleeve.
Cable sleeves, which are sealed by a sleeve head having a flanged opening which is shrinkable into sealing engagement onto a cable inserted into the cable sleeve, are disclosed in U.S. Pat. No. 4,203,000, which was based on German patent application No. 27 31 578. The patent discloses a cable sleeve, which has a divided metal supporting jacket, which is closed on both ends by sleeve heads which consist of a member of thermally shrinkable material. Each of the sleeve heads has a planar wall with an integral cylindrical outer wall portion or flange and at least one flanged opening for forming a cable inlet. Each of the flanged openings is provided with a sealable separating joint formed by an axial slot in the flange which extends through a portion of the wall between the outer wall portion and the flange and also the outer wall portion to enable inserting of an uncut cable into the flanged opening of the sleeve head without threading an end of the cable through the opening. In the region of the separating joint, a web extends between each edge of the slot of the flanged opening to the outer wall portion and these webs are engaged by a support ring. After insertion of the cable, the flanged openings are shrunk onto the inserted cable by a heat shrinking process. Since, in the case of a uniform shrinking, the area of the separating joint also must be shrunk, irregularities can result in the region of the separating joint. These irregularities, which occur particularly during the shrinking of the flange into sealing engagement on a cable having a small diameter, lead to formations of unsealed locations in the contact or the support areas of the joint. This is due to the consequence of the shrinking forces acting uniformly in the circumferential direction which attempts to draw apart the separation joint. In this manner, a gap will develop along a surface line extending in the axial direction of the cable and the separation joint which gaps leads to a breaking of the seal. The gusset regions along the separating joint are particularly endangered by such a gap.
Additional problems also occur from the expansion process used prior to the shrinking step. Each of the cable inlets formed by the flange openings are expanded by means of pressing a conically designed punch or mandrel therethrough. However as a result of this, axial displacements and deformations result due to the frictional forces which occur between the flange opening and the mandrel. These axial displacements or deformations will result in axial stresses, which are relieved during the shrinking process and cause axial displacement to therefore create problems with sealing engagement.